1. Field of the Invention
This invention relates, generally, to data-gathering devices that are used in marine environments. More particularly, it relates to means for protecting such devices from the effects of water exposure.
2. Description of the Prior Art
Untended monitoring devices for sensing, recording, and reporting various environmental conditions are well known. Recent advances include a fiber-optic sensor for the measurement of dissolved CO.sub.2 in seawater currently under development by YSI, Inc., of Yellow Springs, Ohio. The YSI buoys used in marine environments are multi-parameter buoys; in addition to monitoring levels of dissolved CO.sub.2, they also monitor dissolved oxygen pH, pCO.sub.2, water temperature, conductivity, wind speed and direction, solar radiation, air temperature, and the like.
Nor are water quality monitoring devices restricted to seawater applications. They have utility in monitoring water quality parameters in wastewater, drinking water, aquaculture, surface water, groundwater, and estuaries as well.
Another company active in this industry is WET Labs, Inc., of Philonsth, Oreg. It provides underwater optical instrumentation for physical, biological, geological, and chemical characterization of the natural environment. The sensors made by WET Labs, Inc. perform the functions of spectrophotometry, and measure absorption, attenuation, scattering and fluorescence.
Unfortunately, monitoring devices dedicated to marine environments are subjected to the dilatory effects thereof, including corrosion, barnacles, algae, and the like. If a sensor dedicated to monitoring environmental conditions in the sea is exposed for sustained periods of time to the marine environment that it monitors, its useful life is short. Since marine sensors are often mounted in remote, not easily accessible locations, a long useful lifetime is desirable. Moreover, marine sensors may also be expensive, thereby providing another reason why a long service lifetime is preferred.
One way to extend the lifetime of a sensor in a marine environment is to perform a high level of maintenance on the sensor. Frequent removal of barnacles, for example, is mandatory if an ocean-based sensor is to have a commercially acceptable lifetime. Obviously, such frequent cleaning is labor intensive and accordingly quite expensive.
What is needed, then, is an inexpensive means for extending the operative lifetime of a water quality sensor.
However, in view of the prior art taken as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how these needs could be fulfilled.